TY - CHAP M1 - Book, Section TI - Chapter 9. Case–Control Studies A1 - Greenberg, Raymond S. A1 - Daniels, Stephen R. A1 - Flanders, W. Dana A1 - Eley, John William A1 - Boring, John R. PY - 2005 T2 - Medical Epidemiology, 4e AB - A case–control study is an observational study in which subjects are sampled based upon presence or absence of disease and then their prior exposure status is determined. Case–control studies are statistically efficient and cost-effective for the study of rare diseases, and multiple risk factors can be investigated in a case–control study. Newly diagnosed persons with disease are referred to as incident cases, whereas previously existing cases are referred to as prevalent cases. Ideally, the controls should have a prevalence of exposure that is the same as the population of unaffected persons. A population-based study is one in which cases and controls are sampled from a defined population, such as a metropolitan area. A hospital-based sample of cases and controls may be convenient and inexpensive to collect, but may be biased by factors that affect the likelihood of hospitalization for cases and controls. If sampling of cases, controls, or both is influenced by prior exposure history, then a selection bias may be present. Confounding occurs when the apparent effect of the exposure of interest is attributable in whole or in part to some other factor. Matching in a case–control study involves sampling of controls to parallel selected characteristics of cases in order to reduce the likelihood of confounding by the matched features. The odds ratio is a measure of association between the exposure and disease that can be calculated in case–control studies. SN - PB - The McGraw-Hill Companies CY - New York, NY Y2 - 2024/03/28 UR - accessmedicine.mhmedical.com/content.aspx?aid=546046 ER -